Chosen Solution

I recieved a switch from a family member who told me it was overheating, simple fix i thought. after replacing the fan and turning it on i noticed the new fan wasnt spinning up during gameplay either (had the back cover of switch so i could see it). I decided to change the fan once again but to a already fully functioning fan from my switch and it wouldnt spin up either, so now i am lost and have no idea what to do. Any help is appreciated

In the end, Use this guide and double-check before screwing back your back case. Nintendo Switch Fan Replacement